Apparatus for applying corner protectors to pallets

Abstract: An apparatus associable to a known-type strapping machine (1), having a fixed portal (2) and a mobile arch (3), and comprising magazines (4), constrained to the portal (2), for accumulating angle bars (5), and an angle bar moving device (20), constrained to the mobile arch (3), for collecting the angle bars (5) from the magazine (4) and positioning them on the pallet corners.

Description: The invention relates to an apparatus for applying corner protectors (so called "angle bars") to pallets. The long operative chain leading to a final stacking and despatch of vegetable and fruit produce ends with the stacking of the wooden crates or cartons containing the produce on pallets. Pallets are generally parallelepiped in shape and of a standardized size, and have a wooden support base. A whole assembly including the base and a predetermined number of crates stacked on them is normally referred to by the term pallet. Once the cartons or crates have been stacked on the pallet bases, a way has to be found to render the whole stable. This is usually done through a strapping operation, consisting in winding a stiff strap around the pallet using a strapping machine for a predetermined number of circuits at various heights. The alignment of the crates on the bases is never perfect, however, and edges may project from the hypothetical and ideal surface, leading to imperfections in the tightness of the strapping which, during transport of the produce, might cause loss of pallet stability. To obviate this occurrence, during the strapping operation right-angled bars, known as angle bars, are applied to the pallets and the strapping is performed around these. The above is normally a manual task and requires the presence of at least one person to position the angle bars with an elastic band or sticky tape, while the strapping machine performs a sufficient number of circuits to hold the angle bars in position. Obviously, this is a lengthy task and is wasteful of operator time. In the prior art are also known some solutions, disclosed in the patents FR-A-2669002 and US-A-5226280, in which are used mechanical devices for transporting the angle bars to the edges of the pallets. The preamble of claim 1 is based on this prior art. However, both described devices are structurally separated from the pallet and, in particular, the means for moving the angle bars are not integral with the mobile part of the strapping machine. This involves two disadvantages: on one side, the means for moving the angle bars are drived in a completely independent manner and they should generally also comprise a device to rotate the angle bars, since these ones, to reduce the lenght of their shifts, are taken from the extremity of the magazines, that is opposite to the pallet; on the other side, the overall dimensions are increased, because to the dimensions of the strapping machine should also be added those ones of the four necessary magazines. The principal aim of the present invention is to obviate the above-mentioned drawbacks. The invention, as characterized in the claims that follow, solves the problem by integrating the angle bar applicator to the strapping operation. The problem is solved thanks to an apparatus, associated to a traditional strapping machine, comprising some angle bar magazines, constrained to a fixed part of a strapping machine, and means for moving the angle bars, constrained to a mobile part of the strapping machine, which means transport the angle bars from the magazines to an application point on an edge of a pallet. One of the advantages obtained through the present invention consists in the fact that the overall dimensions of the strapping machine are not increased by the joining to an apparatus for applying angle bars to the pallet. Further, an improved version of the invention enables the angle bars to be positioned according to the pallet dimensions, so that the edges are always within reach of the strapping machine. In this solution, pallet position error tolerance is increased and masses are reduced. The invention will be described in more detail hereinunder, with the help of the figures of the drawings, which illustrate a non-exclusive and non-limiting embodiment, and in which: figure 1 is a lateral view of the invention during an operative phase; figure 2 shows the invention in a plan view from above; figure 3 shows a detail of the invention in perspective view; figure 4 shows a detail of the invention in a further embodiment, in a plan view from above; figures 5 and 6 show, respectively in a lateral view and a plan view, further details of the embodiment of figure 4. With reference to the figures, the invention relates to an apparatus for applying angle bars to pallets, associated to a traditional strapping machine 1 with a fixed portal frame 2 and a mobile strap guide or arch 3. The apparatus 18 for applying the angle bars 5 comprises magazines 4 for accumulating the angle bars 5 and means 7 for moving the angle bars 5 from the magazines 4 to the application point. The magazines 4 are generally positioned at the four corners of the pallet 19 and are constrained to the fixed portal frame 2 by special constraints 6. The constraints 6 between the portal 2 and the magazines 4 can be of various type: herein they are represented by vertical sliding guides 8, given by a broken line in figure 1, or, alternatively a fixed projecting rod 9 solid at a first end 10 to the portal 2 and at another end 11 to the magazines. The means 7 can also be variously conformed: for more standardized appplications, which have no need for special adjustment in accordance with pallet positioning and dimensions, the type illustrated in figure 3 is common: each comprises at least one pneumatic cylinder 12 bearing a vertical support 14 at a free end 13, said support 14 being equipped with at least two suckers 15 connected to a vacuum generator 16, which suckers 15 grip and release angle bars 5. Also in figure 3, it can be seen that the free end 13 of each pneumatic cylinder 12 is constrained to a linear element 14 by a spherical joint 17, so that the linear element 14 can self-center during the pallet nearing operation. In the above embodiments, the means for moving the angle bars 5 can act only in a straight line and consequently there are strict limitations on the positioning and the sizes of the pallets 19 which are to be strapped. The only adjustable organ is the free end 13 of the pneumatic cylinders 12, which provides a significant advantage only in the immediate vicinity of the line along which the angle bars 5 move. For this reason (see figure 4), it is advantageous to use moving means 7 which comprise a rectangular-plan device 20 provided with four rods 21. The opposite rods 21 are connected by pneumatic piston pairs 22 supported on idle wheels 23 which allow movement on two horizontal parallel planes, sliding in a guide 24 which is subdivided into two superposed housings 24a, 24b made on the mobile arch 3. Two sleeves 25 are slidable on each rod 21 to deaden the impact of contact with the pallet 19. The facing ends of the sleeves 25 of two contiguous rods 21, placed at different heights, are hinged to a sucker-bearing group 27 which comprises, apart from the vertical support 14 and the suckers 15 connected to the vacuum generator 16, at least two pivots 28 which permit rotation of the rods 21 with respect to the sleeves 25. When the mobile arch 3 reaches a predetermined height for positioning the angle bars 5 removed from the magazine 4, the pneumatic pistons 22 move the rods 21 towards the pallet 19 until the skates 26 contact the pallet 19. Figure 6 shows the positioning of an angle bar 5. The rod 21, here shown in a vertical position, has reached the end of its run, since its skate 26 is already in contact with the pallet 19; in this situation, the sleeve 25v associated to it can only move along the axis of the rod 21 to which it is constrained, opposing a resistance due to the friction of the skate 26 against the pallet 19. This friction, together with the force deriving from the downwards movement of the sleeve 25o, horizontal in figure 6, determines a rotation of the angle bar 5 which aids the reliability of the apparatus 18 (the two movements are indicated by arrows), since the end 29 of the angle bar 5 is moved externalwise of the pallet 19, which otherwise might hinder the correct positioning of the angle bar 5. Finally, the pallets 19 are of such a height that one angle bar 5 for each lateral edge cannot stay straight except after several strapping circuits, since the angle bars are not made in metal or other specially rigid material, but usually in pressed cardboard. It is therefore advisable that the same operation is newly performed when the strapping machine 1 is at about half the height of the pallet 19, taking care that the upper angle bar 5 slightly superposes the lower one, on all four edges. Apart from obtaining greater stiffness this way, lower quality materials (costing less) can be used for the task.

Claims: An apparatus for applying corner protectors (5) to pallets, the apparatus being associated to a strapping machine (1) having a fixed portal frame (2) and a mobile strap guide (3) surrounding the pallet, the apparatus further comprising magazines (4) for holding the corner protectors (5), means (6) for fixing the magazines (4) to the fixed portal frame (2), and means (7) for moving the protectors (5) in order to transport them from the magazines (4) to an application point on the pallet (19), characterized in that said means (7) for moving the protectors (5) are mounted on the mobile strap guide (3) in such a way as to be able to translate vertically together with the strap guide (3). An apparatus as in claim 1, characterized in that the means (7) for moving the protectors (5) comprise a rectangular-plan device (20) constituted by: four rods (21) arranged in pairs on two horizontal parallel planes; two pairs of pneumatic pistons (22), each pair aimed at connecting two opposing rods (21) from the four rods (21); idle support wheels (23), mobile in a guiding means (24) made on the mobile guide (3); two sliding sleeves (25) on each of said four rods (21); a plurality of sucker-bearing groups (27), located at a cross point of a contiguous two rods of said four rods (21), and hinged to facing ends of the sleeves (25) located on the contiguous two of said four rods (21). An apparatus as in claim 1, characterized in that the means (6) for fixing said frame (2) to a totality of said magazines (4) is constituted by vertical sliding guides (8). An apparatus as in claim 1, characterized in that the means (6) for fixing the fixed portal frame (2) to said magazines (4) comprise a fixed projecting rod (9) attached at a first end (10) to the fixed portal frame (2) and at another end (11) to the magazines (4). An apparatus as in claim 1, characterized in that the means (7) for moving the protectors (5) comprise at least one pneumatic cylinder (12) bearing at a free end (13) a vertical support (14) provided with at least two suckers (15) connected to a vacuum generator (16), which at least two suckers (15) determine a gripping and a releasing of the protectors (5). An apparatus as in claim 1, characterized in that it is adapted to apply two protectors (5) in a partially-overlapping fashion to each edge of a pallet (19), so as to increase a final rigidity of the pallet. An apparatus as in claim 2, characterized in that the sleeves (25) exhibit a skate (26) for contacting the pallet (19). An apparatus as in claim 2, characterized in that each sucker-bearing group (27) comprises: a vertical support (14) for at least two suckers (15); at least two vertical pivots (28) for connecting the two contiguous rods (21) of the four rods (21) to the sleeves (25). An apparatus as in claim 2, characterized in that the guiding means (24) exhibits two superposed housings (24a, 24b). An apparatus as in claim 5, characterized in that the free end (13) of each pneumatic cylinder (12) is attached to the support (14) by a spherical joint (17), so as to self-center the support (14) against a pallet (19).

Inventors: LOTTI NEVIO, LOTTI, NEVIO
Applicants: SESTESE OFF MEC, SORMA S P A, OFFICINA MECCANICA SESTESE S.P.A., SORMA S.P.A.
Application year: 1994
Main classification: B65B13
IPC codes: B65B13